2.1 Study site
The study was performed in a desert grassland located in Inner Mongolia,
China (41°46 ’43.6 ”N, 111°53’ 41.7” E; 1456 m a.s.l.). The climate is a
typical mid-temperate continental monsoon climate with a dry and windy
spring, hot summer and cold winter. The average annual precipitation
(2004-2022) is about 232 mm (Figure S1), of which about 85% occurs
during the growing season from May to September. The average annual
temperature during the study period was 3.8℃ (Figure S1), with a mean
diurnal temperature difference of 13-14 ℃. The soil at the study site
has a sandy loam texture and is classified as Kastanozem according to
the Food and Agriculture Organization classification system (FAO, 1993).
The soil (0–10 cm depth) has a soil bulk density of 1.3 g
cm-3, a total N of 1.7 g kg-1, a
total carbon of 16.9 g kg-1 and pH of 8.0. Plant
communities at the study site are dominated by two perennial grasses,Stipa breviflora and Cleistogenes songorica , and one
perennial semi-shrub, Artemisia frigida . Other common species
included Kochia
prostrata , Convolvulus
ammannii and Allium tenuissimum .